Thermomate 18kW Electric Tankless Water Heater vs Thermomate 98,500 BTU Natural Gas Tankless Water Heater: Spec Comparison
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This thermomate 18kw electric tankless water heater vs 98500 btu natural gas comparison helps you choose the right unit. Both are indoor tankless models from ThermoMate designed for on-demand hot water. They share similar flow rates and compact footprints. The main difference is the energy source. One uses electricity, while the other burns natural gas. Each requires specific infrastructure for installation. Read on to see how their specs differ in practice.
Key differences
| Aspect | Thermomate 18kW Electric Tankless Water Heater | Thermomate 98,500 BTU Natural Gas Tankless Water Heater |
|---|---|---|
| Fuel Type | Electric | Natural Gas |
| Power Input | 18kW at 240V | 98,500 BTU/hr |
| Flow Rate | Up to 4.4 GPM | Up to 4 GPM |
| Dimensions | 17.1" H x 13.1" W x 13.1" D | 21.7" H x 13.8" W x 13.8" D |
| Certification | ETL | CSA |
Which one should you choose?
Choose Thermomate 18kW Electric Tankless Water Heater if
- You have a 240V electrical panel with space for two 40-amp breakers.
- You want a slightly higher maximum flow rate of 4.4 GPM.
- You prefer a unit with a lower height profile for easier mounting.
Choose Thermomate 98,500 BTU Natural Gas Tankless Water Heater if
- You have a natural gas line available for connection.
- You want precise temperature stability within ±1°F.
- You prefer a unit certified by CSA for gas safety standards.
Verdict: Choose the electric model if you have the necessary electrical capacity and want a slightly higher flow rate. Choose the gas model if you already have a gas line and want precise temperature control. Both units fit indoor spaces and provide instant hot water.
Electric vs Gas Specs Compared
fuel type
Product A uses electricity, requiring a 208 to 240 Volt supply. You need two double-pole 40 Amp breakers and 8 AWG wiring for this 18 kW unit. Product B runs on natural gas, drawing 98,500 BTU per hour. It connects to a standard 1/2 inch NPT gas line and uses a UL-approved 120 Volt plug for its controls. Your home’s existing infrastructure dictates which fuel source is viable. You cannot switch between them without significant electrical or plumbing upgrades.
flow rate
Product A delivers up to 4.4 gallons per minute. This higher flow supports multiple fixtures or a robust shower pressure. Product B provides up to 4 gallons per minute. It is rated to handle one shower and one faucet simultaneously at a 43°F temperature rise. Both units offer sufficient flow for standard household use. The electric model has a slight advantage in maximum capacity, which matters if you run multiple taps at once.
temperature control
Product A features a digital display allowing adjustments in 1°F increments from 80°F to 140°F. It uses self-modulating technology to regulate energy based on incoming water temperature. Product B uses advanced sensors and a control chip that adjusts heating output 20,000 times per second. It maintains temperature stability within ±1°F. Both offer precise control. The gas model’s rapid adjustment cycle may provide more consistent comfort during fluctuating inlet conditions.
dimensions
Product A measures 17.12 inches high, 13.12 inches wide, and 3.12 inches deep. It is very thin, fitting into tight wall spaces. Product B measures 21 inches high, 13 inches wide, and 7 inches deep. It is taller and significantly deeper than the electric unit. Both are compact compared to tank heaters. The electric model is thinner, making it easier to install in narrow alcoves or behind doors where depth is restricted.
certification
Product A is ETL certified. It includes overheating protection and auto-stop heating when no water is detected. Product B is CSA certified with certificate number 80296889. It features extensive safety protections including boil-dry, freeze, flame-out, overheat, and high-temperature lock. Both meet safety standards for indoor residential use. The gas model lists more specific safety mechanisms in its data, which may provide added peace of mind for gas appliance owners.
Choose the right ThermoMate unit
Homeowner with existing 240V electrical capacity
You need high flow without gas lines. This 18 kW electric model delivers up to 4.4 GPM. It fits tight spaces at 17.12 by 13.12 by 3.12 inches. The digital display lets you adjust temperature in 1-degree increments from 80 to 140 degrees Fahrenheit. It requires two 40 Amp breakers and 8 AWG wiring for proper installation.
User seeking precise temperature stability
You want consistent water heat without fluctuations. This gas unit adjusts heating output 20,000 times per second. Its advanced sensors keep temperature stable within plus or minus 1 degree Fahrenheit. It delivers up to 4 GPM with 98,500 BTU input. The copper heat exchanger ensures efficient heat transfer and corrosion resistance for long-term reliability.
Renter needing easy gas connection
You prefer standard gas fittings over heavy electrical work. This model uses a 1/2 inch NPT gas inlet and a 3 inch OD vent. It includes a UL-approved 120V plug for simple power access. The compact 21 by 13 by 7 inch size saves floor space. CSA certification ensures safe operation for residential indoor use.
The products compared
Thermomate 18kW Electric Tankless Water Heater
Best for: High-flow indoor electric needs with strong wiring
- Fuel Type
- Electric
- Flow Rate
- Up to 4.4GMP
- Wattage
- 18kW
- Installation Location
- Indoor
- Voltage
- 240V
- Temperature Control
- 80°F to 140°F, ±1°F
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This 18kW electric unit heats water in three seconds with a flow rate up to 4.4 GPM at 240V. It features self-modulating technology for 99.8% efficiency and a slim 17.12 x 13.12 x 3.12-inch profile. You get digital control from 80°F to 140°F in 1-degree increments. It suits indoor spots where space is tight and you need instant hot water without a storage tank.
Pros
- 18kW power delivers up to 4.4 GPM flow
- 99.8% efficiency with self-modulating technology
- Digital display adjusts temperature in 1°F increments
- Compact wall-mount design saves floor space
- ETL certified with overheating and leakage protection
Cons
- Requires two 40-amp double-pole breakers and 8AWG wire
- Indoor installation only
- Higher amperage draw than smaller 11kW or 14kW models
Good fit if
- You need a compact unit for tight indoor spaces
- You have the electrical capacity for an 80-amp circuit
- You want precise digital temperature control
Skip if
- You only have a single 40-amp breaker available
- You need outdoor installation capability
- You require a flow rate higher than 4.4 GPM
Verdict: Thermomate 18kW Electric Tankless Water Heater fits homes with strong electrical infrastructure that need high flow in a small footprint. It is ideal for whole-house use in smaller homes or apartments where space and efficiency matter.
Thermomate 98,500 BTU Natural Gas Tankless Water Heater
Best for: Indoor homes needing reliable gas hot water
- Fuel Type
- Natural Gas
- Flow Rate
- Up to 4 GPM
- BTU
- 98,500 BTU
- Installation Location
- Indoor
- Voltage
- 120V
- Temperature Control
- ±1°F
View on Amazon: Thermomate 98,500 BTU Natural Gas Tankless Water Heater Affiliate link
This indoor natural gas unit delivers up to 4 GPM at a 98,500 BTU/hr output. It features a copper heat exchanger for 98% thermal efficiency. The digital control adjusts heating 20,000 times per second for temperature stability within ±1°F. It fits indoor spaces with a compact 21.7-inch height. This model suits homes needing reliable hot water for one shower and one faucet simultaneously.
Pros
- 98,500 BTU/hr heating capacity for rapid hot water
- Up to 4 GPM flow rate for simultaneous use
- 98% thermal efficiency with 0.81 UEF rating
- Temperature stability within ±1°F via advanced sensors
- Multiple safety protections including boil-dry and freeze
Cons
- Indoor installation only, requiring proper venting
- Requires 3/4 inch NPT water connections
- Limited to single shower and one faucet use
Good fit if
- You need high flow for simultaneous fixtures
- You have indoor gas line access
- You want precise temperature control
Skip if
- You require outdoor installation
- You need electric power only
- You want multi-point simultaneous showers
Verdict: Thermomate 98,500 BTU Natural Gas Heater provides steady hot water for households with gas lines. It fits users who need reliable indoor performance for daily showers and sink use.
Specifications side by side
| Spec | Thermomate 18kW Electric Tankless Water Heater | Thermomate 98,500 BTU Natural Gas Tankless Water Heater |
|---|---|---|
| Fuel Type | Electric | Natural Gas |
| Flow Rate | Up to 4.4GMP | Up to 4 GPM |
| BTU | not stated | 98,500 BTU |
| Wattage | 18kW | not stated |
| Installation Location | Indoor | Indoor |
| Voltage | 240V | 120V |
| Temperature Control | 80°F to 140°F, ±1°F | ±1°F |
| Certification | ETL | CSA |
| Dimensions | 17.12" x 13.12" x 3.12" | 21"H × 13"W × 7"D |
| Weight | not stated | 21.2 pounds |
| Size | 240V/18kW | not stated |
| Color | Gray | Silver |
| Model | ET180 | CZ360NG |
Frequently asked questions
Which Thermomate unit is smaller in height?
The 18kW Electric model is shorter. It measures 17.1 inches tall. The Natural Gas unit stands 21.7 inches high. If you have limited vertical clearance, the electric option fits better. Both units share a similar width of around 13 inches.
Does the gas heater weigh more than the electric one?
Yes, the gas model is heavier. It weighs 21.2 pounds. The electric unit does not list a weight in the provided data. Gas heaters often include metal components for combustion, which adds mass compared to simpler electric designs.
Can I install both units indoors?
Yes, both models are designed for indoor installation. The electric unit requires proper electrical wiring. The gas unit needs a gas line and venting. Ensure your home has the correct infrastructure for your chosen fuel type before mounting either device.
What is the difference in color between the two heaters?
The electric model comes in gray. The natural gas version is silver. This is a cosmetic difference that may help you match the unit to your existing decor or utility room aesthetic. The functional specs remain distinct based on fuel type.
Which model requires a 240V power supply?
The 18kW Electric Tankless Water Heater requires a 240V supply. It draws 18 kW of power. The gas model does not use this electrical voltage for heating. It runs on natural gas, though it may need low-voltage power for controls.
Are both units from the same brand?
Yes, both are manufactured by Thermomate. One is model ET180, and the other is CZ360NG. They share the same brand lineage but differ significantly in energy source. This allows you to choose based on your home's existing utility connections.